$(document).ready(function(){
//	检查滚动条是否到了结算栏的位置
	var countHeight=$("#cartBox .itemInfo:last").offset().top+$("#cartBox .itemInfo:last").height();
	var this_scrollTop = $(this).scrollTop();
	if(this_scrollTop>countHeight-document.body.clientHeight ){
		$("#countBox").css("position","absolute");
	}
//	console.log("countHeight:"+countHeight);
//	console.log("bodyHeight:"+document.body.clientHeight);
//	console.log("当前:"+$(this).scrollTop());
	$(window).scroll(function(){
		var this_scrollTop = $(this).scrollTop();
		if(this_scrollTop>countHeight-document.body.clientHeight ){
			$("#countBox").css("position","absolute");
		}
		else{
			$("#countBox").css("position","fixed");
		}
	});
});